The present invention relates generally to information processing environments and, more particularly, to development and execution of database application programs which operate in a Web environment, particularly in the context of Java applets embedded within HTML pages that are displayed at an end user's browser.
Computers are very powerful tools for storing and providing access to vast amounts of information. Computer databases are a common mechanism for storing information on computer systems while providing easy access to users. A typical database is an organized collection of related information stored as “records” having “fields” of information. As an example, a database of employees may have a record for each employee. Here, each record contains fields designating specifics about the employee, such as name, home address, salary, and the like.
Between the actual physical database itself (i.e., the records contained in data pages stored on a storage device) and the users of the system, a database management system or DBMS is typically provided as a software cushion or layer. In essence, the DBMS shields the database user from knowing or even caring about underlying hardware-level details. Typically, all requests from users for access to the data are processed by the DBMS. For example, information may be added or removed from data files, information retrieved from or updated in such files, and so forth, all without user knowledge of underlying system implementation. In this manner, the DBMS provides users with a conceptual view of the database that is removed from the hardware level. The general construction and operation of a database management system is known in the art. See e.g., Date, C., An Introduction to Database Systems, Volume I and II, Addison Wesley, 1990; the disclosure of which is hereby incorporated by reference.
DBMS systems have long since moved from a centralized mainframe environment to a de-centralized or distributed environment. One or more PC “client” systems, for instance, may be connected via a network to one or more server-based database systems (SQL database server). Commercial examples of these “client/server” systems include Powersoft™ clients connected to one or more Sybase SQL Server™ database servers. Both Powersoft™ and Sybase SQL Server™ are available from Sybase, Inc. of Emeryville, Calif. As the migration to client/server continues, each day more and more businesses are run from mission-critical systems which store information on server-based SQL database systems, such as Sybase SQL Server™. As a result, increasingly higher demands are being placed on server-based SQL database systems to provide enterprise-wide decision support—providing timely on-line access to critical business information (e.g., through “queries”). Accordingly, there is much interest in improving the performance of such systems, particularly in the area of database query performance.
In existing PC-based client/server application environments there are situations in which many, perhaps hundreds, of users having widely variant levels of database expertise execute sophisticated database queries frequently and regularly on a single, powerful relational database management system (RDBMS). One example of such a situation is one in which a database is used to track information regarding a company's employees. Such a database is relied upon and used many times a day by management staff, accounting staff, and personnel staff for various purposes. Since the people actually using the database are not necessarily fluent in database languages or procedures, it is necessary to have an effective, i.e., easy to use, and efficient interface between the user and the database itself.
Typically, the interface between the user and the database is programmed in advance by a database programmer using an application development package having various database “tools”, which range in sophistication from a programming language, e.g., the C programming language, to so-called “application builders” which provide software routines to automate some tasks, e.g., window managers to control data presentation effects such as “pop-up” windows, menu bars, and “pull down” menus. Such an interface typically employs graphics, color, and animation, all of which are CPU-intensive functions executed by the front-end desktop computer.
With the ever-increasing movement of computing to the Internet, there is great interest in extending database development tools to leverage the connectivity provided by the Internet. More particularly, developer users are particularly interested in tools that allow application software, including database application programs, to be “hosted” by the user's own browser.